Apparatus and method for lifting aerial cables

ABSTRACT

A portable telescopic lifting apparatus ( 1 ) for lifting aerial cables ( 53 ). The apparatus ( 1 ) comprises a tubular housing ( 2 ), first and second telescopic members ( 3, 4 ) extendible from and retractable into the housing ( 2 ), a drive ( 5, 60 ) for extending and retracting the telescopic members ( 3, 4 ), and a cable-engaging member ( 51 ) attached to the second telescopic member ( 4 ) for lifting one or more aerial cables ( 53 ). The drive ( 5, 60 ) comprises a chain lever block ( 5 ) and a pulley arrangement ( 60 ). In use, the apparatus ( 1 ) is positioned below one or more aerial cables ( 53 ), the chain lever block ( 5 ) is used to raise the first telescopic member ( 3 ), the first telescopic member ( 3 ) extends from within the housing ( 2 ), the second telescopic member ( 4 ) extends from within the first telescopic member ( 3 ), and cable-engaging member ( 51 ) raises the cable/s ( 53 ).

TECHNICAL FIELD

This invention relates to an apparatus and method for lifting aerialcables such as overhead electrified cables. In particular, the inventionconcerns a portable telescopic apparatus for lifting one or more aerialcables.

BACKGROUND ART

A common problem encountered by trucks carrying oversized loads is thattheir journey along a road may be obstructed by an overhead electrifiedcable or other type of aerial cable. The standard practices forovercoming this problem are to lift the cable using hydraulic liftingequipment (ie. a “cherry picker”) or to manually lift and hold the cablewith hand-held “lift sticks”. Two or more cherry pickers and operatorsmay be needed to lift and hold a cable in the lifted position until theoversized load has passed beneath the cable. In situations where thereare multiple aerial cables, the number of operators and cherry pickersneeded to lift the cables will typically increase.

Some of the disadvantages of the above practices are: that they mayinvolve an operator physically lifting and holding a cable for anextended period of time and the cable may weigh as much as 30 kg; sincea cherry picker is typically operated from within a bucket of the cherrypicker, the operator may be in dangerously close proximity of anelectrified cable; and, the practices may be costly and time consuming,particularly when many operators and cherry pickers are required.

It is therefore an object of the present invention to provide a portableapparatus and method for lifting aerial cables that minimises orovercomes at least one of the disadvantages referred to above, or toprovide the public with a useful or commercial choice.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention, there is provideda portable apparatus for lifting at least one aerial cable, saidapparatus comprising:

-   -   an elongate housing;    -   at least a first telescopic member extendible from and        retractable into the elongate housing;    -   a drive operable at the elongate housing for extending and        retracting the first telescopic member; and    -   at least one cable-engaging member positionable by the first        telescopic member for lifting said at least one aerial cable        when the first telescopic member has extended.

Any suitable type of drive can be used. The drive can include, forinstance, an electric motor, a hydraulic motor, an engine, a chain leverblock, a hand winch, a hoist arrangement, a jacking arrangement or anysuitable combination of the aforementioned.

Preferably, the drive comprises a chain lever block. The chain leverblock can be mounted to the elongate housing and the chain of the chainlever block can be attached to a lower end of the first telescopicmember. The block of the chain lever block can be located within theelongate housing and the operative lever of the chain lever block canextend from within the elongate housing. The elongate housing can haveseparate compartments for containing parts of the chain extending fromopposite sides of the block, so as to prevent entanglement of the chain.

The elongate housing can be of any suitable size, shape andconstruction. Preferably, the elongate housing is a tube of rectangularcross-section. The elongate housing can have internal walls/guides toensure that the first telescopic member extends and retracts correctly.

Whilst supporting the aerial cable, the apparatus is free standing andcan pivot relative to the ground to follow movement of the cable.Preferably, a ground-bearing base of the elongate housing is adapted forpivoting. The base can be of any suitable shape, size and construction.Preferably, the base is wedge-shaped and the apparatus can pivotrelative to the ground about an edge of the wedge.

The apparatus can comprise any suitable number of telescopic members. Ina preferred form of the invention, the apparatus includes a secondtelescopic member extendible from and retractable into the firsttelescopic member, and the cable-engaging member is attached to thesecond telescopic member.

The first and second telescopic members can be of any suitable size,shape and construction. Preferably, the first telescopic membercomprises a tube of rectangular cross-section and the second telescopicmember comprises a tube of circular cross-section.

Preferably, the drive further comprises a pulley arrangement forextending and retracting the second telescopic member. The pulleyarrangement can have at least one sheave attached to an upper end of thefirst telescopic member and a flexible tie of the pulley arrangement canextend around the sheave and have respective ends attached to a lowerend of the second telescopic member and to a lower end of the elongatehousing. With this arrangement, when the first telescopic member israised with the chain lever block, the second telescopic member extendsabout twice as far as the first telescopic member. The flexible tie canbe, for instance, a wire cable or a cord.

The apparatus can have a locking mechanism for ensuring that the firstand second telescopic members cannot extend or retract unless the chainlever block is first operated. Any suitable type of locking mechanismcan be used.

The cable-engaging member can be of any suitable size, shape andconstruction. Depending on how many telescopic members the apparatushas, the cable-engaging member can be attached to the second telescopicmember or to first telescopic member. The cable-engaging member can beattached in any suitable way. The apparatus can have any suitable numberof cable-engaging members.

The cable-engaging member preferably has a body and a headpieceextending from the body. A lower end of the body can be removablyattached to an upper end of the second telescopic member. Preferably,the body is attached such that the cable-engaging member and telescopicmember cannot rotate relative to one another. This may be achieved byproviding the second telescopic member and body with, for instance, apin and slot arrangement, a tongue and groove arrangement, or a bayonetarrangement.

The cable-engaging member can have a fork, tines, a groove, a channel, arecess or any other suitable formation by which a cable can be engagedand lifted. The apparatus can be used to lift a plurality of cables atany one time in which case the cable-engaging member can have aplurality of forks, grooves etc. The forks, grooves etc. can be locatedat the headpiece and/or the body.

In one embodiment of the invention, the headpiece has an undulatingsurface, much like the working end of a rake, wherein individual cablesare receivable within separate grooves of the undulating surface. Withthis arrangement, the cables can be kept in isolation from one anotherwhen being lifted. In another embodiment of the invention, the headpieceand/or body has at least one fork or recess for engaging and lifting atleast one cable.

Preferably, the apparatus is compact and lightweight. The apparatus canconsist of any suitable material or materials such as, for example,metal, plastics material, and composites. When used for liftingelectrified cables, the apparatus, or parts thereof, can be insulated.For instance, the cable-engaging member can be insulated.

According to a second aspect of the invention there is provided a methodfor raising at least one aerial cable, said method comprising the stepsof:

-   -   a) positioning a lifting apparatus beneath an aerial cable, said        apparatus comprising:    -   a housing;    -   at least a first telescopic member extendible from and        retractable into the housing;    -   a drive operable at the housing for extending and retracting the        first telescopic member; and    -   at least one cable-engaging member positionable by the first        telescopic member for lifting said at least one aerial cable        when the first telescopic member has extended; and    -   b) lifting the aerial cable.

The housing can be of any suitable size, shape and construction. Thehousing can be in the form of a stand. Whilst supporting the aerialcable, the apparatus is free standing and can pivot relative to theground to follow movement of the cable. Preferably, the housing istubular.

Preferably, the apparatus includes a second telescopic member extendiblefrom and retractable into the first telescopic member, and thecable-engaging member is attached to the second telescopic member.

Preferably, the cable-engaging member can lift multiple aerial cables inisolation from one another at the same time.

The apparatus can have other features as described in respect of thefirst aspect of the invention.

The term “comprise”, or variations of the term such as “comprises” or“comprising”, are used herein to denote the inclusion of a statedinteger or stated integers but not to exclude any other integer or anyother integers, unless in the context or usage an exclusiveinterpretation of the term is required.

Best modes for carrying out the invention will now be described withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front elevation view of part of a portable aerial cablelifting apparatus when fully extended, according to an embodiment of theinvention;

FIG. 2 shows the apparatus of FIG. 1 when fully retracted;

FIG. 3 is a top plan view of part of the apparatus shown in FIG. 1;

FIG. 4 is a side sectional view taken along plane A-A of the apparatusshown in FIG. 3;

FIG. 5 is a side sectional view taken along plane B-B of the apparatusshown in FIG. 3;

FIG. 6 is a front sectional view taken along plane C-C of the apparatusshown in FIG. 3;

FIG. 7 is a partly detailed front elevation view of part of theapparatus shown in FIG. 1;

FIG. 8 is a front elevation view of a cable-engaging member for theapparatus shown in FIG. 1, according to an embodiment of the invention;

FIG. 9 is a front elevation view of a cable-engaging member for theapparatus shown in FIG. 1, according to an embodiment of the invention;and

FIG. 10 is a front elevation view of part of the apparatus shown in FIG.1 but having a cable-engaging member, according to an embodiment of theinvention.

BEST MODES FOR CARRYING OUT THE INVENTION

In all of the drawings, like reference numerals refer to like parts.

Referring first to FIG. 10, there is shown a portable aerial cablelifting apparatus 1 comprising an elongate housing 2, a first telescopicmember 3, a second telescopic member 4, a drive (not shown) operable atthe housing 2, and a cable-engaging member 51 for lifting one or moreaerial cables 53. The drive comprises a chain lever block 5 and a pulleyarrangement 60.

Referring now to FIGS. 1 to 7, a first telescopic member 3 is extendablefrom and retractable into the housing 2, and a second telescopic member4 is extendable from and retractable into the first telescopic member 3.

As seen in FIG. 4, the chain lever block 5 has a block 61, a chain 16extending over the block 61, and a lever 12 for operating the block 61.

The housing 2 is tubular, it has a ground-bearing base 10 and foursidewalls 11 (only some of which have been labelled) extendingtherefrom. The base 10 is wedge-shaped and the apparatus 1 can pivotrelative to the ground about an edge of the wedge. Internal sidewalls13, 18 and elongate nylon guides 17 (only some of which have beenlabelled) ensure that the first telescopic member 3 extends and retractscorrectly within the housing 2 (see FIG. 3). Sidewalls 13 and 18 extendfrom the base 10 to a position below the block 61. The sidewalls 11, 13,18 together provide two compartments 14, 15. The compartments 14, 15collect and contain parts of the chain 16 hanging from opposite sides ofthe block 61, so as to prevent entanglement of the chain 16. A liftingflange 20 extends from a lower end of the first telescopic member 3between sidewalls 13 and 18, and the chain 16 is attached to the flange20. The block 5 is mounted to a sidewall 11 of the housing 2 forrotation relative thereto. Lever 12 extends from the sidewall 11.

The first telescopic member 3 comprises a tube of rectangularcross-section and the second telescopic member 4 comprises a tube ofcircular cross-section. The housing 2 and telescopic members 3, 4consist of aluminum or composite materials (eg. Kevlar®) that will notbuckle when placed under load. A pin 40 extends diametrically across anupper region of the second telescopic member 4, as seen in FIGS. 3 and5. A lifting flange 42 extends from a lower region of the secondtelescopic member 4, as seen in FIG. 3. Flange 42 prevents the secondtelescopic member 4 from rotating within the first telescopic member 3.

Referring now to FIGS. 3 to 7, the pulley arrangement 60 includes a mainsheave 30, two additional smaller sheaves 31 and a wire cable 34. Asseen in FIGS. 4 and 5, an angle bracket 33 mounts sheaves 30 and 31 to afront sidewall 32 of the first telescopic member 3. The front sidewall32 has a pair of slits (not shown) through which extend sheaves 31. Thecable 34 extends partly around each of the sheaves 30, 31 and throughthe slits. As seen in FIGS. 6 and 7, one end 35 of the cable 34 isattached to flange 42 and the other end 36 of the cable 34 is attachedto the base 10 of the housing 2, so that when the first telescopicmember 3 extends the second telescopic member 4 extends as well.

FIGS. 8 to 10 show different types of cable-engaging members 50, 51, 52for lifting aerial cables 53. Each member 50, 51, 52 basically comprisesa cylindrical body 57 and a headpiece 70 for engaging one or more cables53. A lower end of the body 57 fits within the second telescopic member4 and has a slot 54 that receives pin 40. The pin 40 prevents member 50from rotating.

The headpiece 70 of member 50 comprises a fork 55 for lifting a singlecable 53. Member 52 differs from member 50 in that it has a second fork56 of sorts (for a second cable 53) extending from the body 57. Member51 differs from members 50 and 52 in that its headpiece 70 has anundulating surface 58. Each groove 59 of the undulating surface 58 canreceive a cable 53. Undulating surface 58 enables multiple cables 53 tobe lifted at any one time and to be kept in isolation from one another.

In use, the apparatus 1, with the telescopic members 3, 4 fullyretracted, is positioned beneath one or more aerial cables (eg. overheadpower lines) that need to be raised, so that, for instance, a truckcarrying an oversized load may pass therebeneath. A suitablecable-engaging member 50, 51, 52 is attached to the second telescopicmember 4. The chain lever block 5 is operated, the first telescopicmember 3 extends from within the housing 2 and the second telescopicmember 4 extends from the first telescopic member 3. If multiple cablesneed to be lifted, then either member 51 or 52 is used. If a singlecable needs to be lifted, then any one of members 50 to 52 can be used.The telescopic members 3, 4 are extended until there is sufficientclearance between a top of the oversized load and the cable/s. The chainlever block 5 is locked such that the telescopic members 3, 4 cannotretract by accident. If lifting electrified cables, then the apparatus 1is insulated. For instance, the cable-engaging member 50, 51, 52 and/orthe second telescopic member 4 can consist of a non-conductive materialor can be insulated with rubber. After the truck has passed beneath thecable/s, the telescopic members 3, 4 are retracted and the member 50,51, 52 may be detached.

Once an aerial cable has been lifted, the apparatus 1 is free standingand the apparatus 1 can, if necessary, pivot relative to the ground. Thepivoting action enables the apparatus 1 to follow the movement of thelifted cable (such as when the cable sways when blown by wind) andreduces the bending moment on the apparatus 1.

The advantages of the invention include that: the apparatus can be usedto raise one or more cables at any one time; since the apparatus is freestanding whilst supporting the cable/s, other cables can be lifted by asingle operator using additional like apparatuses; the apparatus can beused on uneven or sloping ground as it has a small ground-bearingsurface; in the retracted state, the apparatus can be easily handled,transported and stored; an operator need not rely on physical strengthto lift and hold a cable in the lifted position; since the apparatus isoperable at ground level, an operator need not be in close proximity ofan electrified cable; specialised machinery such as cherry pickers arenot required; and, the apparatus can be positioned and extended in atime efficient manner with a great degree of accuracy and control.

Whilst the above has been given by way of illustrative example of theinvention, many modifications and variations may be made thereto bypersons skilled in the art without departing from the broad scope andambit of the invention as herein set forth.

1. A portable apparatus for lifting at least one aerial cable, saidapparatus comprising: an elongate housing; at least a first telescopicmember extendible from and retractable into the elongate housing; adrive operable at the elongate housing for extending and retracting thefirst telescopic member; and at least one cable-engaging memberpositionable by the first telescopic member for lifting said at leastone aerial cable when the first telescopic member has extended.
 2. Theapparatus of claim 1, wherein the drive comprises a chain lever blockmounted to the elongate housing and the chain of the chain lever blockis attached to a lower end of the first telescopic member.
 3. Theapparatus of claim 2, wherein a block of the chain lever block islocated within the elongate housing, the operative lever of the chainlever block extends from within the elongate housing and the elongatehousing has separate compartments for containing parts of the chainextending from opposite sides of the block.
 4. The apparatus of claim 3,wherein the elongate housing has internal guides for the firsttelescopic member.
 5. The apparatus of claim 2 further comprising asecond telescopic member extendible from and retractable into the firsttelescopic member, and the cable-engaging member is attached to thesecond telescopic member.
 6. The apparatus of claim 5, wherein the drivefurther comprises a pulley arrangement for extending and retracting thesecond telescopic member.
 7. The apparatus of claim 6, wherein thepulley arrangement has at least one sheave attached to an upper end ofthe first telescopic member and a flexible tie of the pulley arrangementextends around the sheave and has respective ends attached to a lowerend of the second telescopic member and to a lower end of the elongatehousing.
 8. The apparatus of claim 7, wherein when the first telescopicmember is raised with the chain lever block, the second telescopicmember extends about twice as far as the first telescopic member.
 9. Theapparatus of claim 5, wherein the cable-engaging member has a bodyremovably attached to an upper end of the second telescopic member and aheadpiece extending from the body.
 10. The apparatus of claim 9, whereinthe headpiece and/or body has at least one fork or recess by which atleast one said cable can be engaged and lifted.
 11. The apparatus ofclaim 10, wherein the headpiece has an undulating surface and individualsaid cables are receivable within separate grooves of the undulatingsurface.
 12. The apparatus of claim 1, wherein a ground-bearing base ofthe elongate housing is wedge-shaped and the apparatus can pivotrelative to the ground about an edge of the wedge.
 13. A method forraising at least one aerial cable, said method comprising the steps of:a) positioning a lifting apparatus beneath an aerial cable, saidapparatus comprising: a housing; at least a first telescopic memberextendible from and retractable into the housing; a drive operable atthe housing for extending and retracting the first telescopic member;and at least one cable-engaging member positionable by the firsttelescopic member for lifting said at least one aerial cable when thefirst telescopic member has extended; and b) lifting the aerial cable.14. The method of claim 13, wherein the apparatus is free standing onlywhilst supporting the aerial cable.
 15. The method of claim 13 furthercomprising a second telescopic member extendible from and retractableinto the first telescopic member, and the cable-engaging member isattached to the second telescopic member.
 16. The method of claim 13,wherein the cable-engaging member lifts multiple aerial cables inisolation from one another at the same time.
 17. The method of claim 13,wherein the apparatus is pivotable relative to the ground.
 18. Themethod of claim 17, wherein the housing is tubular.
 19. The method ofclaim 18, wherein a ground-bearing base of the housing is wedge-shapedand the apparatus can pivot relative to the ground about an edge of thewedge.